Why does a rigid body with Convex Hull collision bounds not move in BGE?
Enable Physics at your material.

Hints (outside of the question):

You named your objects and bricks - I like that. It was really helpful when looking at the scene.
The meshes have way too much faces for a game. They do not need that many for that little detail. I strongly suggest to remove the subsurf modifier(s). You can use smooth shading instead.
The floor creates projectiles. This was really distracting when analyzing your file. I would not expect a floor to behave this way. A separate object (e.g. called RandomProjectileSpawner) could do that job. You can add/remove it without loosing the scene's floor. You could even have more than one.
The dimensions of the projectile's physics shapes are way too large. They collide with the physics mesh of object Ship right after creation. I suggest to enable collision bounds at the physics tab on the projectiles. A box shape should be good enough.
Be aware the physics engine has problems with small travelling objects. It might happen that they do not collide with another face and suddenly are inside of an object, or that a collision does not get registered.

I hope it helps